The present invention concerns a gate valve to simultaneously shut off or clear two rectangular passage openings that are provided between two vacuum chambers which are aligned with one another and which have a low height and a large width on the order of magnitude of up to several meters, wherein the gate valve has two valve plates opposite one another to close the passage openings.
Gate valves of the preceding type are needed, for example, in sputtering units in which glass passes several vacuum chambers placed one behind the other to be coated with an antireflection layer, for example, by sputtering. In such production units several vacuum chambers are constructed mostly as sputtering chambers. A one-gate chamber and many times also a buffer chamber are connected upstream from it, such that it is necessary for the glass to be able to move into the pertinent chamber via passage openings that can be closed.
Up to now the passage openings have been closed by flaps or traditional sliders. Since the passage openings, however, can be several meters wide, in the manufacturing of glass, for example, the sealing of such flaps or sliders causes difficulties. With flaps there is the problem that their swivel axis must run precisely parallel to the passage opening so that the flap lies uniformly against the sealing over its entire length. With sliders there is wear and tear due to the friction of the sliders on the seals and thus there are leaks in the course of time.
Therefore, it is an object of the invention to overcome the problem of constructing a gate valve of the type described herein so that, with the least possible expense, a reliable sealing is attained and its tightness is impaired as little as possible by wear and tear.